1. Field of the Invention
The invention relates to a high-velocity carburetor for an Otto engine comprising a slide for changing the cross-section of the suction pipe, a nozzle connection receiving nozzles and a profiled nozzle needle seated on the slide and controlling the cross-section of the nozzle.
2. Description of the Prior Art
Such a high-velocity carburetor with slide does not possess a throttle valve so that in contrast to a variable venturi carburetor practically the full suction pipe pressure is present on the nozzle in the region of the slide. Consequently, particularly in the partial load region, very high flow rates are effective at the nozzle and thus excellent spraying properties are present.
According to the size of the annular gap between nozzle and needle in the intermediate chamber between the two nozzles a vacuum is built up in proportion to the suction pipe vacuum. The cross-section relation of the nozzles and/or the ascending profile of the nozzle needle determine the amount of the negative pressure existing between the nozzles in the intermediate chamber. It is possible by the profiling of the nozzle needle to assign a fuel quantity to a specific slide position, i.e. to a determined vacuum. However this fuel amount is not always in the optimum operating range of the engine. If one selects for a specific nozzle needle profile characteristic the fuel apportioning in such a manner that an enriched mixture condition results, then it is possible to reduce by air admixture in the intermediate chamber the vacuum existing therein. Thereby the fuel amount can be reduced and the fuel-air mixture is weakened. The air admixture in addition to the regulation of the fuel-air mixture, also effects a further improvement of the atomization.